U.S. patent application number 12/523805 was filed with the patent office on 2010-02-25 for method for producing circuit substrate, and circuit substrate.
This patent application is currently assigned to Lintec Corporation. Invention is credited to Tatsuo Fukuda, Naofumi Izumi, Masahito Nakabayashi.
Application Number | 20100044887 12/523805 |
Document ID | / |
Family ID | 39635996 |
Filed Date | 2010-02-25 |
United States Patent
Application |
20100044887 |
Kind Code |
A1 |
Fukuda; Tatsuo ; et
al. |
February 25, 2010 |
METHOD FOR PRODUCING CIRCUIT SUBSTRATE, AND CIRCUIT SUBSTRATE
Abstract
The method for producing a circuit substrate of the present
invention is characterized in that the circuit substrate is
produced using as sheet a circuit substrate sheet including an
uncured layer a part of which, the part being other than a part at
which a circuit chip is disposed, is selectively curable before or
after disposal of said circuit chip, wherein the uncured layer has
a softness that enables embedding of the circuit chip in the
circuit substrate sheet upon pressing the circuit chip that has
been disposed on a surface of the uncured layer. According to the
method for producing the circuit substrate of the present
invention, the circuit chip can be embedded inwards with high
accuracy, and the circuit substrate can be produced easily with
high accuracy.
Inventors: |
Fukuda; Tatsuo;
(Itabashi-ku, JP) ; Nakabayashi; Masahito;
(Itabashi-ku, JP) ; Izumi; Naofumi; (Itabashi-ku,
JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W., SUITE 800
WASHINGTON
DC
20037
US
|
Assignee: |
Lintec Corporation
Itabashi-ku, Tokyo
JP
|
Family ID: |
39635996 |
Appl. No.: |
12/523805 |
Filed: |
January 17, 2008 |
PCT Filed: |
January 17, 2008 |
PCT NO: |
PCT/JP2008/050478 |
371 Date: |
July 20, 2009 |
Current U.S.
Class: |
257/787 ;
257/E21.502; 257/E23.116; 438/127 |
Current CPC
Class: |
H05K 2203/016 20130101;
H05K 1/185 20130101; H05K 2203/1469 20130101; H05K 2203/1476
20130101; H05K 2201/0108 20130101; H01L 23/5389 20130101; H01L
2924/0002 20130101; H01L 2924/0002 20130101; H05K 3/0011 20130101;
H05K 3/007 20130101; H01L 21/56 20130101; H05K 2203/056 20130101;
H01L 2924/00 20130101 |
Class at
Publication: |
257/787 ;
438/127; 257/E21.502; 257/E23.116 |
International
Class: |
H01L 21/56 20060101
H01L021/56; H01L 23/28 20060101 H01L023/28 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 18, 2007 |
JP |
2007-009568 |
Claims
1. (canceled)
2. (canceled)
3. (canceled)
4. A method for producing a circuit substrate comprising providing
a circuit substrate sheet having an uncured layer that is curable
by irradiation with active energy ray; disposing a circuit chip on
a predetermined part of said uncured layer; thereafter embedding
said circuit chip into said uncured layer; and irradiating with
said active energy ray said circuit substrate sheet having said
circuit chip embedded therein, to cure said circuit substrate
sheet, for obtaining said circuit substrate having said circuit
chip embedded therein, wherein: before embedding said circuit chip
into said uncured layer, a part, that is other than said
predetermined part, of said uncured layer is selectively cured to
be a cured portion, whereas said predetermined part is left to be
an uncured portion.
5. The method for producing the circuit substrate according to
claim 4, wherein, before disposing the circuit chip on the surface
of said uncured layer, said selective formation of said uncured
portion and said cured portion is performed by bonding to the
surface of said uncured layer a mask for selectively shielding the
active energy ray and irradiating said uncured layer with the
active energy ray from a side of said bonded mask, followed by said
disposal of the circuit chip on the surface of said uncured
portion, and pressing of the circuit chip for said embedding of
said circuit chip in said uncured layer.
6. The method for producing the circuit substrate according to
claim 4, wherein, before disposing the circuit chip on the surface
of said uncured layer, said selective formation of said uncured
portion and said cured portion is performed by bonding on said
uncured layer a perforated having holes selectively provided and
irradiating said uncured layer with the active energy ray, followed
by said disposal of the circuit chip on the surface of said uncured
portion, and pressing of the circuit chip for said embedding of
said circuit chip in said uncured layer.
7. The method for producing the circuit substrate according to
claim 4, wherein, after disposing the circuit chip on the surface
of said uncured layer, said selective formation of said uncured
portion and said cured portion is performed by irradiating said
uncured layer with the active energy ray from a side of the
disposed circuit chip on said uncured layer, followed by pressing
of said circuit chip to for said embedding of said circuit chip in
said uncured layer.
8. A circuit substrate obtained by the method for producing the
circuit substrate according to claim 4.
9. A circuit substrate sheet comprising an uncured layer that is
curable upon receiving irradiation with an active energy ray, said
circuit substrate sheet being capable of becoming a circuit
substrate having a circuit chip embedded therein, by selectively
disposing the circuit chip on a predetermined part of said uncured
layer, embedding said disposed circuit chip into said uncured
layer, and irradiating said layer with said active energy ray,
wherein: in said circuit substrate sheet, a part, that is other
than said predetermined part, of said uncured layer is selectively
cured to be a cured portion, whereas said predetermined part is
left to be an uncured portion.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method for producing a
circuit substrate whereby a circuit chip can be embedded easily
with high accuracy by disposing the circuit chip on a surface
thereof and then pressing the circuit chip inwards, and also
relates to a circuit substrate obtained using the method for
producing the circuit substrate.
BACKGROUND ART
[0002] In a circuit substrate that composes a display such as a
liquid crystal display and an organic EL display, a microelectronic
device for controlling each pixel of the display is disposed, and a
circuit that transmits input and output signals of the
microelectronic device is formed. Conventionally, in this circuit
substrate, the microelectronic device is disposed by producing the
device directly on a glass circuit substrate in situ. That is, the
microelectronic device such as a thin film transistor (TFT) is
formed by laminating an insulation film and a semiconductor film
sequentially on the glass circuit substrate using a vacuum
technology such as CVD (chemical vapor deposition) and then
applying to these deposited films the same steps as those for
producing a semiconductor integrated circuit. Such microelectronic
devices are formed in the vicinity of each pixel and control on/off
and contrasting density of each pixel, to realize an image
formation on the display.
[0003] In recent years, the displays having a large screen of 40 to
100 inches have been desired and already commercially distributed.
However, the method for producing the circuit substrate that
requires a multistep process using the aforementioned glass
substrate and vacuum technology is a obstacle to reduce cost. For
achieving widespread use of the large screen displays, the cost
must be reduced. Therefore, there has been sought a method for
producing the circuit substrate whereby the cost for producing the
large screen display is reduced.
[0004] Recently, a new technology has been proposed for addressing
to the aforementioned demand for cost reduction of the large screen
display (Patent Document 1). In the technology disclosed in this
Patent Document 1, a circuit chip produced separately is used as
the microelectronic device, and a plastic substrate that is
inexpensive and has a light weight is used as the circuit
substrate. Applying a printing technology, the circuit chip is
disposed on the plastic substrate, and the circuit is produced,
which enables production of a large screen display at a low
cost.
[0005] Patent Document 1: JP 2003-248436-A
DISCLOSURE OF INVENTION
Problem to be Solved by the Invention
[0006] In the technology disclosed in Patent Document 1, holes for
disposing the circuit chips are previously created at predetermined
positions on the plastic substrate. Meanwhile, a nickel film
responsive to a magnet is laminated on a surface of the circuit
chip. The predetermined number of these circuit chips having the
nickel film are magnetically secured in accordance with a
predetermined pattern. These circuit chips are engaged in the holes
on the plastic substrate at once, and then a wiring pattern is
formed.
[0007] In the aforementioned conventional technology, it is
necessary that the circuit chips are disposed on the plastic
substrate and the holes for embedding the chips are previously
created on the substrate. The embedding holes having a larger size
than the size of the circuit chips would render easier disposal of
the circuit chips, but would also deteriorate accuracy of the
disposing position of the circuit chips on the circuit substrate.
Conversely, the embedding holes having a size close to the size of
the circuit chips would render high accuracy of the disposing
position of the circuit chip on the substrate, but would also
increase difficulty in disposal operation of the circuit chips,
i.e., embedding operation of the circuit chips in the embedding
holes.
[0008] The present invention has been made in the light of the
above circumstance, and it is an object of the present invention to
provide a method for producing a circuit substrate whereby disposal
and embedding of a circuit chip can be performed easily and
precisely without forming an embedding hole for the circuit chip on
the substrate, and a circuit substrate obtained using such a method
for producing the circuit substrate.
Means for Solving Problem
[0009] In order to solve the above problems, the present inventors
have studied extensively and reached the present invention. That
is, the method for producing a circuit substrate of the present
invention comprises embedding a circuit chip in a circuit substrate
sheet, said circuit substrate sheet including an uncured layer a
part of which, said part being other than a part at which said
circuit chip is disposed, is selectively curable before or after
disposal of said circuit chip, and said uncured layer having a
softness that enables embedding of said circuit chip in said
circuit substrate sheet upon pressing said circuit chip that has
been disposed on a surface of said uncured layer.
[0010] In the method for producing the circuit substrate of the
present invention, it is preferable that the uncured layer that
composes the circuit substrate sheet is formed to have a thickness
that exceeds a thickness of the circuit chip.
[0011] A material forming the uncured layer may be any material as
long as an uncured portion and a cured portion can be selectively
formed, although preferable is an active energy ray-curable resin
that is curable by irradiation with active energy ray, because
therewith selective formation of the uncured portion and the cured
portion can be performed easily and precisely.
[0012] Alternatively, the method for producing a circuit substrate
of the present invention comprises: a circuit chip embedding step
of providing a circuit substrate sheet having an uncured layer that
is curable by irradiation with active energy ray, disposing a
circuit chip on a surface of said uncured layer, and pressing said
circuit chip to embed said circuit chip into said uncured layer;
and a circuit substrate sheet curing step of irradiating with said
active energy ray said circuit substrate sheet having said circuit
chip embedded therein, to cure said circuit substrate sheet, for
obtaining said circuit substrate having said circuit chip embedded
therein.
[0013] In the method for producing the circuit substrate, before
disposing the circuit chip on the surface of the uncured layer, an
uncured portion and a cured portion may be selectively formed by
bonding to the surface of the uncured layer a mask that selectively
shields the active energy ray, and then irradiating the uncured
layer with the active energy ray from the side on which the mask is
bonded. The circuit chip may then be disposed on the surface of the
uncured portion.
[0014] In the method for producing the circuit substrate, before
disposing the circuit chip on the surface of the uncured layer, the
uncured portion and the cured portion may be selectively formed by
bonding to the uncured layer a perforated release sheet having
openings selectively provided, and then irradiating the uncured
layer with the active energy ray. The circuit chip may then be
disposed on the surface of the uncured portion.
[0015] In the method for producing the circuit substrate of the
present invention, after disposing the circuit chip on the surface
of the uncured layer, the uncured portion and the cured portion may
be selectively formed by irradiating the uncured layer with the
active energy ray from a side of the uncured layer on which the
circuit chip is disposed, and subsequently the circuit chip may be
pressed on the surface of the uncured layer to embed the circuit
chip into the uncured layer.
[0016] The circuit substrate of the present invention is a circuit
substrate obtained by any of the aforementioned methods for
producing the circuit substrate of the present invention.
EFFECT OF THE INVENTION
[0017] According to the present invention, the circuit chip is
pressed inwards after the circuit chip being disposed on the
surface, which renders possible to provide a method for a circuit
substrate whereby the circuit chip can be embedded easily with high
accuracy, and the circuit substrate produced thereby.
BRIEF DESCRIPTION OF DRAWINGS
[0018] FIG. 1 is a side cross-sectional view of a circuit substrate
sheet composed of an active energy ray-curable resin.
[0019] FIG. 2 is a side cross-sectional view of a state wherein the
circuit substrate sheet is irradiated with an active energy ray
through a mask to selectively form an uncured portion.
[0020] FIG. 3 is a side cross-sectional view of the circuit
substrate sheet in a state wherein the uncured portion and the
cured portion are exposed.
[0021] FIG. 4 is a side cross-sectional view of a state wherein a
circuit chip is disposed on the circuit substrate sheet.
[0022] FIG. 5 is a side cross-sectional view of a state wherein the
circuit chip disposed on a surface of the circuit substrate sheet
is embedded into the circuit substrate sheet by a plane pressing
machine.
[0023] FIG. 6 is a side cross-sectional view showing a state
wherein the circuit substrate sheet in which the circuit chip has
been embedded is irradiated with an active energy ray for
curing.
[0024] FIG. 7 is a side cross-sectional view of the circuit
substrate obtained by completing embedding of the circuit chip and
curing of the circuit substrate sheet.
[0025] FIG. 8 is a side cross-sectional view of a state wherein a
perforated release sheet is cohered to an exposed side of the
circuit substrate sheet composed of the active energy ray-curable
resin.
[0026] FIG. 9 is a side cross-sectional view of a state of
selectively forming an uncured portion and a cured portion by
irradiating the circuit substrate sheet with an active energy ray
through the perforated release sheet under an oxygen-containing
atmosphere.
[0027] FIG. 10 is a side cross-sectional view of the circuit
substrate sheet in a state wherein the uncured portion and the
cured portion are exposed.
[0028] FIG. 11 is a side cross-sectional view showing a state
wherein a circuit chip is disposed on the uncured layer of the
circuit substrate sheet.
[0029] FIG. 12 is a side cross-sectional view showing a state
wherein the uncured portion and the cured portion are selectively
formed by irradiation with an active energy ray using the circuit
chip on the uncured layer of the circuit substrate sheet as a
mask.
EXPLANATIONS OF LETTERS AND NUMERALS
[0030] 1 Circuit substrate sheet [0031] 2 Uncured layer [0032] 2a
Uncured portion [0033] 2b Cured portion [0034] 3 Glass substrate
[0035] 4 Release sheet of heavy-releasing type [0036] 5 Mask [0037]
6 Circuit chip [0038] 10 Plane pressing machine [0039] 11 Release
sheet [0040] 12 Glass substrate [0041] 13 Circuit substrate [0042]
20 Perforated release sheet [0043] 20a Hole
BEST MODE FOR CARRYING OUT THE INVENTION
Active Energy Ray-Curable Resin
[0044] A material for a circuit substrate sheet for producing the
circuit substrate of the present invention is not particularly
limited as long as selective curing of the material at a part other
than a part at which a circuit chip is disposed can be performed
before or after disposal of the circuit chip, and pressing of the
circuit chip disposed on a surface thereof can cause embedment of
the circuit chip in the circuit substrate sheet, although an active
energy ray-curable resin is suitably used since therewith selective
formation of an uncured layer can be performed easily, and disposal
and embedment of the circuit chip can be performed easily and
presicely. This active energy ray-curable resin is a resin that
polymerizes and cures upon irradiation with an active energy ray
such as ultraviolet ray and electron beam.
[0045] Examples of the active energy ray-curable resin for use in
the present invention may include (1) resins containing an acrylic
polymer and an active energy ray-polymerizable oligomer and/or
polymerizable monomer and, if desired, a photopolymerization
initiator, and (2) resins containing an acrylic polymer having a
side chain to which an active energy ray-curable functional group
including a polymerizable unsaturated group is introduced, and also
containing, if desired, a photopolymerization initiator.
[0046] In the resin (1), preferable examples of the acrylic polymer
may include copolymers of (meth)acrylate having 1 to 20 carbon
atoms in an alkyl group in its ester moiety with an optional
monomer having a functional group possessing active hydrogen used
and another optional monomer, i.e., (meth)acrylate copolymers.
[0047] Examples of (meth)acrylate having 1 to 20 carbon atoms in
the alkyl group in its ester moiety may include methyl
(meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl
(meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate,
cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl
(meth)acrylate, palmityl (meth)acrylate and stearyl (meth)acrylate.
Any one of them may be used alone or two or more thereof may be
used in combination.
[0048] Meanwhile, examples of the optional monomer having a
functional group possessing active hydrogen for use may include
hydroxyalkyl (meth)acrylate such as 2-hydroxyethyl (meth)acrylate,
2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate,
2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate and
4-hydroxybutyl (meth)acrylate; monoalkylaminoalkyl (meth)acrylate
such as monomethylaminoethyl (meth)acrylate and
monoethylaminopropyl (meth)acrylate; and ethylenic unsaturated
carboxylic acids such as acrylic acid, methacrylic acid, crotonic
acid, maleic acid, itaconic acid and citraconic acid. Any one of
these monomers may be used alone or two or more thereof may be used
in combination.
[0049] In the (meth)acrylate copolymer, the amount of
(meth)acrylate is 5 to 100% by weight, preferably 50 to 95% by
weight, and the amount of the monomer having the functional group
possessing active hydrogen is 0 to 95% by weight, preferably 5 to
50% by weight.
[0050] Examples of another optional monomer for use may include
vinyl esters such as vinyl acetate and vinyl propionate; olefins
such as ethylene, propylene and isobutylene; halogenated olefins
such as vinyl chloride and vinylidene chloride; styrene-based
monomer such as styrene and .alpha.-methylstyrene; diene-based
monomer such as butadiene, isoprene and chloroprene; nitrile-based
monomers such as acrylonitrile and methacrylonitrile; and
acrylamides such as acrylamide, N-methylacrylamide and
N,N-dimethylacrylamide. Any one of them may be used alone or two or
more thereof may be used in combination. The amount of these
monomers contained in the (meth)acrylate copolymer may be 0 to 30%
by weight.
[0051] With the (meth)acrylate copolymer for use as the acrylic
polymer in the resin, copolymerization form thereof is not
particularly limited, and may be any of random, block and graft
copolymerization. Its molecular weight is preferably 300,000 or
more in terms of weight average molecular weight.
[0052] The aforementioned weight average molecular weight is a
value in terms of polystyrene measured by a gel permeation
chromatography (GPC) method.
[0053] In the present invention, one species of (meth)acrylate
copolymer may be used alone. Alternatively, two or more thereof may
be used in combination.
[0054] Examples of the active energy ray-polymerizable oligomer may
include polyester acrylate-based oligomers, epoxy acrylate-based
oligomers, urethane acrylate-based oligomers, polyether
acrylate-based oligomers, polybutadiene acrylate-based oligomers
and silicone acrylate-based oligomers.
[0055] The weight average molecular weight of the polymerizable
oligomer is selected in the range of preferably 500 to 100,000,
more preferably 1,000 to 70,000 and still more preferably 3,000 to
40,000 as the value in terms of standard polystyrene measured by
the GPC method.
[0056] On species of polymerizable oligomer may be used alone.
Alternatively, two or more thereof may be used in combination.
[0057] Meanwhile, examples of the active energy ray-polymerizable
monomer may include monofunctional acrylates such as cyclohexyl
(meth)acrylate, 2-ethylhexyl (meth)acrylate, morpholine
(meth)acrylate and isobonyl (meth)acrylate; 1,4-butanediol
di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol
di(meth)acrylate, polyethylene glycol di(meth)acrylate, neopentyl
glycol adipate di(meth)acrylate, neopentyl glycol hydroxypivalate
di(meth)acrylate, dicyclopentanyl di(meth)acrylate,
caprolactone-modified dicyclopentenyl di(meth)acrylate,
ethyleneoxide-modified phosphate di(meth)acrylate, allylated
cyclohexyl di(meth)acrylate, isocyanurate di(meth)acrylate,
trimethylolpropane tri(meth)acrylate, dipentaerythritol
tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene
oxide-modified trimethylolpropane tri(meth)acrylate,
tris(acryloxyethyl) isocyanurate, propionic acid-modified
dipentaerythritol penta(meth)acrylate, dipentaerythritol
hexa(meth)acrylate and caprolactone-modified dipentaerythritol
hexa(meth)acrylate. Any one of these polymerizable monomers may be
used alone or two or more thereof may be used in combination.
[0058] The amount of these polymerizable oligomers and
polymerizable monomers to be used may usually be 3 to 500 parts by
weight based on 100 parts by weight of a solid content in the
(meth)acrylate copolymer.
[0059] As the active energy ray, an ultraviolet ray or an electron
beam is usually used, and when the ultraviolet ray is used, a
photopolymerization initiator is used. Examples of this
photopolymerization initiator may include benzoin, benzoin methyl
ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin
n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylamino
acetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one,
2,2-dimethoxy-2-phenylacetophenone,
2,2-diethoxy-2-phenylacetophenone,
2-hydroxy-2-methyl-1-phenylpropane-1-one, 1-hydroxycyclohexyl
phenyl ketone,
2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propane-1-one,
4-(2-hydroxyethoxy)phenyl-2(hydroxy-2-propyl) ketone, benzophenone,
p-phenylbenzophenone, 4,4'-diethylaminobenzophenone,
dicyclobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone,
2-tertiary-butylanthraquinone, 2-aminoanthraquinone,
2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone,
2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyl dimethyl
ketal, acetophenone dimethyl ketal, acetophenone dimethyl ketal,
p-dimethylamine benzoate and
oligo(2-hydroxy-2-methyl-1-[4-(1-propenyl)phenyl]propanone). Any
one of them may be used alone or two or more thereof may be used in
combination.
[0060] The amount of such a polymerization initiator to be blended
is usually 0.1 to 10 parts by weight based on 100 parts by weight
of the solid content in the aforementioned active energy
ray-curable resin.
[0061] Subsequently, examples of the acrylic polymer having a side
chain to which an active energy ray-curable functional group
including a polymerizable unsaturated group is introduced may
include those obtained by preparing the aforementioned
(meth)acrylate polymer having a side chain to which an active point
such as --COOH, --NCO, epoxy group, --OH or --NH.sub.2 is
introduced, and then reacting this active point with a compound
having the polymerizable unsaturated group, to thereby introduce
the energy ray-curable functional group having the polymerizable
unsaturated group into the side chain of the acrylic polymer.
[0062] In order to introduce the active point into the acrylic
polymer, a monomer or an oligomer having the functional group such
as --COOH, --NCO, epoxy group, --OH or --NH.sub.2 and the
polymerizable unsaturated group may be allowed to coexist in a
reaction system when the acrylic polymer is produced. Specifically,
upon producing the acrylic polymer in accordance with the
aforementioned description about the resin (1), (meth)acrylic acid,
etc. may be used for introducing --COOH, 2-(meth)acryloyloxyethyl
isocyanate, etc. may be used for introducing --NCO, glycidyl
(meth)acrylate, etc. may be used for introducing epoxy group,
2-hydroxyethyl (meth)acrylate or 1,6-hexanediol mono(meth)acrylate,
etc. may be used for introducing --OH, and N-methyl
(meth)acrylamide, etc. may be used for introducing --NH.sub.2.
[0063] The compound having the polymerizable unsaturated group for
the reaction with the active point may be appropriately selected
among, for example, 2-(meth)acryloyloxyethyl isocyanate, glycidyl
(meth)acrylate, pentaerythritol mono(meth)acrylate,
dipentaerythritol mono (meth)acrylate, dipentaerythritol mono
(meth)acrylate, trimethylolpropane mono(meth)acrylate, depending on
the type of the active point.
[0064] In this way, it is possible to obtain the acrylic polymer,
i.e. the (meth)acrylate copolymer, wherein the active energy
ray-curable functional group including the polymerizable
unsaturated group is introduced to the side chain of the acrylic
polymer through the active point.
[0065] This (meth)acrylate copolymer to which the active energy
ray-curable functional group has been introduced has a weight
average molecular weight of preferably 100,000 or more and
particularly preferably 300,000 or more. The weight average
molecular weight is the value in terms of polystyrene measured by
the GPC method.
[0066] As the optionally used photopolymerization initiator, the
photopolymerization initiators exemplified in the description of
the aforementioned resin (1) may be used.
[0067] If desired, to the aforementioned active energy ray-curable
resins (1) and (2), it is possible to add crosslinking agents,
tackifiers, antioxidants, ultraviolet ray absorbers, light
stabilizers, softeners and fillers, within the range in which the
effects of the present invention are not impaired.
[0068] Examples of the crosslinking agents may include
polyisocyanate compounds, epoxy resins, melamine resins, urea
resins, dialdehydes, methylol polymers, aziridine-based compounds,
metal chelate compounds, metal alkoxide and metal salts, and the
polyisocyanate compound is preferably used. This crosslinking agent
can be added at 0 to 30 parts by weight based on 100 parts by
weight of the solid content in the aforementioned (meth)acrylate
copolymer.
[0069] Examples of the polyisocyanate compound may include aromatic
polyisocyanate such as tolylene diisocyanate, diphenylmethane
diisocyanate and xylylene diisocyanate; aliphatic polyisocyanate
such as hexamethylene diisocyanate; alicyclic polyisocyanate such
as isophorone diisocyanate and hydrogenated diphenylmethane
diisocyanate; as well as biuret and isocyanurate thereof, and
further adducts thereof which are reactants with a low molecular
active hydrogen-containing compound such as ethylene glycol,
neopentyl glycol, trimethylol propane and castor oil. Any one of
these crosslinking agents may be used alone, or two or more thereof
may be used in combination.
[0070] Concerning the aforementioned active energy ray-curable
resins (1) and (2), the energy ray-curable resin [0071] may contain
the (meth)acrylate copolymer of (2) having the side chain including
the polymerizable, unsaturated, active energy ray-curable group.
Likewise, the active energy ray-curable resin (2) may contain the
acrylic polymer, the active energy ray-polymerizable oligomer or
the active energy ray-polymerizable monomer of (1). If desired, a
solvent may also be added. The solvent to be used may be
appropriately selected among publicly known solvents that exhibit a
good solubility with the active energy ray-curable resins (1) and
(2) and are inactive with the resins (1) and (2). Examples of such
a solvent may include toluene, xylene, methanol, ethanol,
isobutanol, n-butanol, acetone, methyl ethyl ketone,
tetrahydrofuran and ethyl acetate. Any one of them may be used
alone or two or more thereof may be used in combination.
[0072] Among the active energy rays, the ultraviolet ray may be
preferably used in terms of versatility and economical efficiency.
As a lamp that generates the ultraviolet ray, a high pressure
mercury lamp, a metal hydride lamp, a xenon lamp and an
electrodeless ultraviolet ray lamp are available. The irradiation
amount of the ultraviolet ray is appropriately selected. For
example, the light amount is 1 to 1,500 mJ/cm.sup.2 and the
illuminance is about 10 to 500 mW/cm.sup.2.
[0073] The circuit substrate sheet for use in the present invention
may be formed with the active energy ray-curable resin in
accordance with the following procedures.
(Formation of Circuit Substrate Sheet)
[0074] A coating solution of the active energy ray-curable resin is
prepared. This coating solution is applied onto a release treated
side of a release sheet (release sheet of heavy-releasing type)
which has a base for release sheet and a releasing agent layer
provided on one side thereof.
[0075] If the solution includes a solvent, heating and drying is
then performed. Thereby a sheet on which an uncured layer composed
of the active energy ray-curable resin has been formed is obtained.
The coating solution is applied using a knife coater, a roll
coater, a bar coater, a blade coater or a gravure coater, and dried
under conditions of room temperature to 150.degree. C., preferably
60 to 130.degree. C. for 1 to 10 minutes. As the release sheet,
those publicly known may be used, and examples thereof may include
those having a base for release sheet such as a polyethylene film,
a polypropylene film, polyethylene terephthalate film or a
polyethylene naphthalate film and a releasing agent layer provided
thereon by applying a releasing agent such as a silicone resin, an
alkyd resin or a long chain alkyl resin. The thickness of this
release sheet is usually about 20 to 150 .mu.m.
[0076] Likewise, the aforementioned coating solution is separately
applied onto the release treated side of another release sheet
(release sheet of light-release type) which has a base for release
sheet and a releasing agent layer provided on one side thereof.
Heating and drying is then performed if necessary. Thereby another
sheet having an uncured layer composed of the active energy
ray-curable resin is obtained. The release force of the release
sheet used herein is set to be smaller than the that of the release
sheet of heavy-releasing type.
[0077] The uncured layer on the release sheet of light-release type
is laminated on the uncured layer on the release sheet of
heavy-releasing type, and the release sheet of light-release type
is peeled. This lamination step is repeated, to thereby obtain a
circuit substrate sheet having an uncured layer of a predetermined
thickness that is composed of the active energy ray-curable resin
sandwiched with the release sheet of heavy-releasing type and the
release sheet of light-release type. The thickness of the uncured
layer is 30 to 1,000 .mu.m and preferably 50 to 500 .mu.m.
[0078] The uncured layer composed of the active energy ray-curable
resin is in an uncured state until being irradiated with the active
energy ray, and the resin in the uncured state has a softness that
enables embedding of the circuit chip. Therefore, if a desired
number of the circuit chips are disposed on this uncured layer by
any arbitrary method and subsequently these circuit chips are
vertically pressed onto the surface of the uncured layer using,
e.g., a plane pressing machine, then the circuit chips can be
embedded in the uncured layer. After embedding the circuit chips,
entire irradiation of the uncured layer with the active energy ray
would cause curing of the uncured layer, whereby the circuit chips
are firmly fixed and a sufficient physical strength as the circuit
substrate is realized.
[0079] Selective formation of the uncured portion and the cured
portion may be performed before or after disposing the circuit
chips on the uncured layer.
[0080] To leave uncured the region on which the circuit chip are to
be disposed and circumferences thereof in the depth direction while
curing other regions before disposing the circuit chips on the
uncured layer, there are mainly two methods. In one method, a mask
for selectively shielding the active energy ray is bonded on the
surface of the uncured layer, and the side on which the mask has
been bonded is irradiated with the active energy ray, whereby the
irradiated portion is cured and the non-irradiated portion shielded
by the mask is left uncured. Examples of the mask for shielding the
active energy ray may include those having a base plate made of,
e.g., a quartz glass and a metal thin film of, e.g., chromium
formed thereon as a shielding portion. The other method utilizes a
phenomenon inhibiting curing of an active energy ray-curable resin
whose curing process proceeds by radical polymerization, wherein
the phenomenon occurs when the resin is in contact with an
oxygen-containing atmosphere such as an air. That is, a release
sheet through which the active energy ray can pass is selectively
perforated to obtain a perforated release sheet, which is then
placed on the uncured layer and they are irradiated with the active
energy ray. Although the active energy ray is given to the entire
surface of the cured layer, the portion covered with the sheet and
therefore not contacted with oxygen is cured, whereas the portion
contacted with the oxygen-containing atmosphere through the holes
is left uncured as a result of oxygen's inhibition of curing. This
method utilizes this phenomenon for selectively creating the
uncured portion. It is preferable that the side of the uncured
layer on which the perforated release sheet is not bonded is
attached to, e.g., a glass substrate for avoiding contact with the
oxygen-containing atmosphere. For the perforated release sheet, the
aforementioned release sheet may be used. The hole can be created
by any publicly known method such as a method with a heated needle
or a laser. The thickness of the perforated release sheet is
usually about 20 to 150 .mu.m.
[0081] To leave uncured the region on which the circuit chip has
disposed and circumferences thereof in the depth direction while
curing other regions after disposing the circuit chips on the
uncured layer, the irradiation with the active energy ray may be
performed using the circuit chip as the mask. That is, after
disposing the circuit chips on the surface of the uncured layer,
the uncured layer is irradiated with the active energy ray from
above the surface of the uncured layer on which the circuit chips
have been disposed. By this irradiation, the uncured portion and
the cured portion are selectively formed using the circuit chips as
the masks. Subsequently, the circuit chips are pressed to embed the
circuit chips in the uncured layer.
[0082] The method for producing the circuit substrate using each of
the aforementioned embedding method will be described hereinbelow
with reference to the figures.
[0083] (Method for Producing Circuit Substrate (1))
[0084] Referring to FIG. 1, a release sheet of light-release type
(not shown in the figure) on a circuit substrate sheet 1 produced
as described above is peeled from an uncured layer 2 and the
circuit substrate sheet is bonded to a glass substrate 3 such as a
soda lime or a quartz glass. At that time, a release sheet of
heavy-releasing type 4 which is capable of passing the active
energy ray therethrough is left unpeeled.
[0085] As shown in FIG. 2, a mask 5 having a predetermined number
(one in the figure) of parts which shields the active energy ray in
a form of a predetermined pattern is bonded on the release sheet of
heavy-releasing type 4, and irradiation with the active energy ray
is performed onto the side on which the mask has been bonded. As
the mask, the one having a quartz glass and a thin film of chromium
thereon at a part for shielding the active energy ray can be
used.
[0086] As a result of being irradiated with the active energy ray,
the part shielded from the irradiation of the active energy ray by
the mask 5 is left as an uncured portion 2a, and the remaining
portion irradiated with the active energy ray becomes a cured
portion 2b. Subsequently, as shown in FIG. 3, the release sheet of
heavy-releasing type 4 on the other side is peeled to expose the
uncured portion 2a and the cured portion 2b.
[0087] Subsequently, as shown in FIG. 4, the predetermined number
(one in the figure) of the circuit chips 6 is disposed by any
arbitrary method on the surface of the uncured portion 2a of the
circuit substrate sheet.
[0088] The circuit substrate sheet 1 on which the predetermined
number (one in the figure) of the circuit chips 6 has been disposed
at the predetermined position is mounted together with the glass
substrate 3 in a plane pressing machine 10 as shown in FIG. 5.
Subsequently, a release sheet 11 and a glass substrate 12 are
placed sequentially on the circuit substrate sheet 1, and they are
gradually pressed from above and below. As the release sheet 11 and
the glass substrate 12, those enumerated previously may be used.
Then, the circuit chip 6 disposed on the surface is embedded in the
circuit substrate sheet 1 because the uncured portion on which the
circuit chip 6 has been disposed is uncured and soft. The surface
of the circuit chip and the surface of the circuit substrate sheet
1 thereby compose continuous plane. At that time, pressure is
evenly applied to the circuit substrate sheet 1 by the lower glass
substrate 3, the upper glass substrate 12 and release sheet 11,
whereby a flatness of the surface is not impaired even after the
circuit chip 6 is embedded. The depth direction along which the
circuit chip 6 is embedded is controlled by the surrounding cured
portion 2b, whereby the circuit chip 6 is embedded in the sheet
without causing displacement in a horizontal direction to the sheet
surface.
[0089] After the circuit chip 6 is embedded, the circuit substrate
sheet is unloaded from the plane pressing machine 10 as the upper
release sheet 11 and glass substrate 12 and the lower glass
substrate 3 are kept attached. Subsequently, as shown in FIG. 6,
the entire surface of the circuit substrate sheet 1 is irradiated
with the active energy ray from the side of the lower glass
substrate 3 to cure the uncured portion 2a of the circuit substrate
sheet 1. After curing, the upper glass substrate 12 and release
sheet 11 are removed, to obtain a circuit substrate 13 wherein the
entire circuit substrate sheet has been cured after embedding the
desired circuit chip 6.
[0090] Subsequently, the circuit substrate 13 is furnished with
wirings for controlling the pixels by well-known electrode and
wiring formation methods such as vacuum deposition, sputtering and
photolithography, to complete the circuit substrate for the
display.
[0091] In the method for producing the circuit substrate
aforementioned with reference to FIGS. 1 to 7, the uncured portion
2a and the cured portion 2b are formed using the mask 5.
Alternatively in the present invention, it is also possible to
selectively form an uncured adhesive portion by bringing a
predetermined local area into contact with oxygen upon being
irradiated with the active energy ray to cause inhibition against
curing. This method will be described hereinbelow with reference to
FIGS. 8 to 10.
[0092] (Method for Producing Circuit Substrate (2))
[0093] Referring to FIG. 8, the release sheet of light-release type
(not shown in the figure) on the circuit substrate sheet 1 produced
as described previously is peeled from the uncured layer 2, and the
circuit substrate sheet is bonded to the glass substrate 3.
Subsequently, the release sheet of heavy-releasing type on the
other side (not shown in the figure) is peeled, and instead
thereof, a perforated release sheet 20 is bonded. This perforated
release sheet 20 has a predetermined number (one in the figure) of
holes 20a formed in a predetermined pattern.
[0094] Subsequently as shown in FIG. 9, irradiation with the active
energy ray is performed onto the side on which the perforated
release sheet 20 has been bonded toward the uncured layer 2. As
mentioned in the above, the hole 20a has been created in the
perforated release sheet 20, and thus, the uncured layer 2 in the
region of the hole 20a is in contact with air. Keeping this state,
the uncured layer 2 is irradiated with the active energy ray under
the atmosphere such as air containing oxygen, whereby the entire
region of the uncured layer 2 is photocured, except for the region
in contact with the air through the hole 20a in which curing does
not occur because curing is inhibited by oxygen in the air. Thus,
the uncured portion 2a is selectively formed, and the remaining
portion becomes the cured portion 2b. In FIG. 9, irradiation with
the active energy ray is performed onto the side on which the
perforated release sheet 20 has been bonded, but may also be
performed onto the side of the glass substrate 3.
[0095] As mentioned in the above, the uncured portion 2a and the
cured portion 2b are selectively formed as a result of the
irradiation using the perforated release sheet 20 under the
atmosphere such as air containing oxygen. Subsequently, the
perforated release sheet 20 is peeled to expose the uncured portion
2a and the cured portion 2b as shown in FIG. 10. Subsequently, the
circuit substrate 13 is obtained in accordance with the steps shown
in aforementioned FIGS. 4 to 7.
[0096] In the aforementioned methods for producing the circuit
substrate (1) and (2), the uncured portion 2a and the cured portion
2b are formed before the circuit chip 6 is disposed on the uncured
layer 2. Alternatively, in the present invention, it is also
possible to form the uncured portion 2a and the cured portion 2b
after disposing the circuit chip 6 on the uncured layer 2. This
method will be described hereinbelow with reference to FIGS. 11 and
12.
[0097] (Method for Producing Circuit Substrate (3))
[0098] Referring to FIG. 11, the release sheet of light-release
type (not shown in the figure) of the circuit substrate sheet 1
produced as described previously is peeled from the uncured layer
2, and the circuit substrate sheet is bonded to the glass substrate
3. Subsequently, the release sheet of heavy-releasing type (not
shown in the figure) is peeled, and the predetermined number (one
in the figure) of the circuit chips 6 is disposed in the
predetermined pattern on the exposed uncured layer 2.
[0099] Subsequently, as shown in FIG. 12, irradiation with the
active energy ray is performed toward the uncured layer 2 onto the
side thereon on which the circuit chip has been disposed. As a
result, the circuit chip 6 serves as a mask, and the portion under
the circuit chip 6 becomes the uncured portion 2a. The remaining
portion becomes the cured portion 2b. Subsequently, the circuit
substrate 13 is obtained in accordance with the steps shown in
aforementioned FIGS. 4 to 7.
EXAMPLES
[0100] Examples of the method for producing the circuit substrate
of the present invention will be discussed hereinbelow. The
Examples shown below are only exemplifications for suitably
explaining the present invention, and by no means limit the present
invention.
[0101] Examples 1 and 2 to be discussed hereinbelow are examples
which were performed in accordance with the method for producing
the circuit substrate (1) previously described with reference to
FIGS. 1 to 7. Likewise, Example 3 is an example which was performed
in accordance with the method for producing the circuit substrate
(2) previously described with reference to FIGS. 8 to 10, and
Example 4 is an example which was performed in accordance with the
method for producing the circuit substrate (3) previously described
with reference to FIGS. 11 and 12.
Example 1
Formation of Circuit Substrate Sheet
[0102] 80 parts by weight of butyl acrylate (supplied from Kanto
Chemical Co., Inc.) and 20 parts by weight of acrylic acid
(supplied from Kanto Chemical Co., Inc.) were reacted in a mixed
solvent of ethyl acetate/methyl ethyl ketone (weight ratio: 50:50),
to obtain an acrylate copolymer (solid content: 35% by weight), to
which 2-methacryloyloxyethyl isocyanate (supplied from Kokusan
Chemical Co., Ltd.) was added so that the amount thereof was 30
equivalents per 100 equivalents of acrylic acid in the copolymer.
The mixture was reacted under a nitrogen atmosphere at 40.degree.
C. for 48 hours to yield an acrylic copolymer having a weight
average molecular weight of 850,000 and having a side chain to
which an active energy ray-curable functional group including an
active energy ray-curable group.
[0103] To 100 parts by weight in terms of solid content of the
resulting acrylic copolymer solution to which the active energy
ray-curable functional group is introduced, were dissolved 3.0
Parts by weight of 2,2-dimethoxy-1,2-diphenylethane-1-one (brand
name: Irgacure 651 supplied from Ciba Specialty Chemicals) as a
photopolymerization initiator, 100 parts by weight (solid content:
80 parts by weight) of a composition composed of active energy
ray-polymerizable polyfunctional monomer and oligomer (brand name:
14-29B(NPI) supplied from Dainichiseika Color & Chemicals Mfg.
Co., Ltd.) and 1.2 parts by weight (solid content: 0.45 parts) of a
crosslinking agent composed of a polyisocyanate compound (brand
name: Oriban BHS-8515 supplied from Toyo Ink Mfg. Co., Ltd.) were
dissolved. Finally, methyl ethyl ketone was added thereto for
adjusting the solid content concentration to 40% by weight, and the
mixture was stirred until an even solution was obtained, to obtain
a coating solution.
[0104] The coating solution thus prepared was applied using a knife
coater onto a release treated side of a release sheet of
heavy-releasing type (brand name: SP-PET3811 supplied from LINTEC
Corporation) which has a polyethylene terephthalate film having a
thickness of 38 .mu.m and a silicone-based releasing agent layer
provided on one side of that film. The layers were heated and dried
at 90.degree. C. for 90 seconds to form an uncured layer composed
of the active energy ray-curable resin having a thickness of 50
.mu.m.
[0105] Likewise, the coating solution was separately applied onto
the release treated side of a release sheet of light-release type
(brand name: SP-PET3801 supplied from LINTEC Corporation) which has
a polyethylene terephthalate film having a thickness of 38 .mu.m
and a silicone-based releasing agent layer provided on one side of
that film. The layers were heated and dried at 90.degree. C. for 90
seconds to form an uncured layer composed of the active energy
ray-curable resin having of the thickness of 50 .mu.m.
[0106] The uncured layer on the release sheet of light-release type
was laminated on the uncured layer on the release sheet of
heavy-releasing type, and the release sheet of light-release type
was peeled therefrom. This lamination process was repeated, to
thereby obtain a circuit substrate sheet having an uncured layer
composed of the active energy ray-curable resin and having the
thickness of 400 .mu.m, sandwiched with the release sheet of
heavy-releasing type and the release sheet of light-release
type.
[0107] (Selective Formation of Uncured Portion and Cured
Portion)
[0108] The release sheet of light-release type on the circuit
substrate sheet having the uncured layer was peeled, and the
circuit substrate sheet was bonded to a soda lime glass substrate
of 5 cm.times.5 cm. Keeping this state, on the release sheet of
heavy-releasing type at the other side, a mask was bonded. Via this
mask, the circuit substrate sheet was irradiated with ultraviolet
ray under conditions of an illuminance of 400 mW/cm.sup.2 and a
light amount of 315 mJ/cm.sup.2 using an electrodeless lamp (H
bulb, supplied from Fusion Inc.) as a light source. As the mask, a
mask having a quartz glass and a thin film of chromium formed on
the glass for shielding the ultraviolet ray (size of shielding
part: lengthwise 520 .mu.m.times.crosswise 520 .mu.m, interval 1740
.mu.m) was used. By being irradiated with the ultraviolet ray from
above the mask, four uncured portions having the size of lengthwise
520 .mu.m.times.crosswise 520 .mu.m were formed in the uncured
layer, and the remaining portion was cured.
[0109] (Embedding of Circuit Chip in Circuit Substrate Sheet)
[0110] The release sheet of heavy-releasing type of the circuit
substrate sheet was peeled, and each of four circuit chips
(lengthwise 500 .mu.m.times.crosswise 500 .mu.m and thickness 200
.mu.m) was disposed on the surface of each of the four uncured
portions.
[0111] (Embedding of Circuit Chips, and Curing of Circuit Substrate
Sheet)
[0112] On the circuit substrate sheet on which the circuit chips
had been disposed on the glass substrate, a separately prepared
soda lime glass plate of 5 cm.times.5 cm as another glass substrate
was thrusted via a release sheet (brand name: SP-PET3801 supplied
from LINTEC Corporation). They were pressed at a pressure of 0.3
MPa for 5 minutes using a plane pressing machine. After restoring a
normal pressure, the circuit substrate sheet together with the
release sheet, the upper soda lime glass and the lower glass
substrate was removed from the plane pressing machine. The circuit
substrate sheet was irradiated with ultraviolet ray under
conditions of an illuminance of 400 mW/cm.sup.2 and a light amount
of 315 mJ/cm.sup.2 using an electrodeless lamp (H bulb, supplied
from Fusion Inc.) as a light source. The irradiation was performed
from the lower glass substrate side having no circuit chip, to
thereby cure the uncured portion. Subsequently, the soda lime glass
plate and the release sheet on the upper side of the circuit
substrate sheet were removed, to thereby obtain a circuit substrate
on the lower soda lime glass substrate in which the four circuit
chips had been embedded at a desired position.
Example 2
[0113] The embedment of the circuit chips in the circuit substrate
sheet and the curing of the circuit substrate sheet were performed
in the same manner as in Example 1, except that a mask on which a
shielding part having a size of lengthwise 800
.mu.m.times.crosswise 800 .mu.m (interval 1740 .mu.m) had been
formed was used as the mask that shielded the ultraviolet ray to
the circuit substrate sheet, to thereby obtain a circuit
substrate.
Example 3
[0114] A circuit substrate was obtained in the same manner as in
Example 1, except that the step of selectively forming the uncured
portion and the cured portion in the circuit substrate sheet in
Example 1 was changed as follows.
[0115] (Selective Formation of Uncured Portion and Cured
Portion)
[0116] The release sheet of light-release type on the circuit
substrate sheet having the uncured layer was peeled, and the
circuit substrate sheet was bonded onto the soda lime glass
substrate of 5 cm.times.5 cm.
[0117] Subsequently, a release sheet (brand name: SP-PET3801
supplied from LINTEC Corporation) having a polyethylene
terephthalate film having a thickness of 38 .mu.m and a
silicone-based releasing agent layer provided on one side of that
film was prepared. The release sheet was subjected to application
of a carbon dioxide laser, to create square holes of 520
.mu.m.times.520 .mu.m (interval 1740 .mu.m) in the regions
corresponding to four places for disposing the circuit chips
(perforated release sheet).
[0118] The perforated release sheet obtained by the aforementioned
procedure was bonded on a surface of the uncured layer which had
been exposed by peeling the release sheet of heavy-releasing type
of the circuit substrate sheet. Keeping this state, the uncured
layer of the circuit substrate sheet was irradiated with
ultraviolet ray onto the side of the perforated release sheet under
an air atmosphere (oxygen gas-containing atmosphere). The
irradiation was performed under conditions of an illuminance of 400
mW/cm.sup.2 and a light amount of 100 mJ/cm.sup.2 using an
electrodeless lamp (H bulb, supplied from Fusion Inc.) as the light
source. As a result, four parts of uncured portions each having a
size of lengthwise 520 .mu.m.times.crosswise 520 .mu.m were formed
on the uncured layer, and the remaining portion became a cured
portion. Subsequently, circuit chips were embedded in the circuit
substrate sheet and the circuit substrate sheet was cured, to
obtain a circuit substrate in the same manner as in Example 1.
Example 4
[0119] A circuit substrate was obtained in the same manner as in
Example 1, except that the process before embedding the circuit
chip in Example 1 was changed as follows.
[0120] (Selective Formation of Uncured Portion and Cured
Portion)
[0121] The release sheet of light-release type on the circuit
substrate sheet having the uncured layer was peeled, and the
exposed uncured layer was bonded onto the soda lime glass substrate
of 5 cm.times.5 cm. The release sheet of heavy-releasing type on
the surface at the other side was then peeled to expose the uncured
layer.
[0122] Subsequently, four circuit chips were disposed in a
predetermined pattern on the uncured layer. Keeping this state, the
uncured layer of the circuit substrate sheet was irradiated with
ultraviolet ray from right above onto the side on which the circuit
chips had been disposed. Irradiation was performed under conditions
of an illuminance of 400 mW/cm.sup.2 and a light amount of 600
mJ/cm.sup.2 using the electrodeless lamp (H bulb, supplied from
Fusion Inc.) as a light source. As a result, uncured portions
having almost the same size as the circuit chip size (lengthwise
500 .mu.m.times.crosswise 500 .mu.m) were formed in the uncured
layer under the circuit chips, and the remaining portion became a
cured portion. Subsequently, embedment of the circuit chips in the
circuit substrate sheet and curing of the circuit substrate sheet
was performed in the same manner as in Example 1, to obtain a
circuit substrate.
Reference Example 1
[0123] A circuit substrate was obtained in the same manner as in
Example 1, except that the circuit substrate sheet was not
irradiated with the ultraviolet ray to leave the entire region as
an uncured adhesive resion before disposing the circuit chips.
Reference Example 2
[0124] A circuit substrate was obtained in the same manner as in
Example 1, except that the size of the shielding portion in the
mask used was changed to lengthwise 1300 .mu.m.times.crosswise 1300
.mu.m (interval 1740 .mu.m).
[0125] (Evaluation)
[0126] The surface size of the uncured portion, and the
displacement width (.mu.m) in a horizontal direction between the
position of circuit chip at the beginning of embedding and the
position of the circuit chip at the completion of embedding were
measured as to each Example. The evaluation test was performed 10
times, and a mean value thereof was calculated. The results were
shown in Table 1.
TABLE-US-00001 TABLE 1 Surface size of the uncured Position
displacement width portion (lengthwise of the circuit chip before
.mu.m .times. crosswise .mu.m) and after embedment (.mu.m) Example
1 520 .times. 520 9 Example 2 800 .times. 800 18 Example 3 520
.times. 520 9 Example 4 500 .times. 500 0 Comparative Entire area
of the 814 Example 1 uncured layer Comparative 1300 .times. 1300 52
Example 2
[0127] As is evident from Table 1, the method for producing the
circuit substrate of the present invention enables easy and precise
embedment and securing of a circuit chip on a circuit substrate
sheet with a small displacement distance. The method for producing
the circuit substrate of the present invention enables easy
production of a circuit substrate in which a circuit chip has been
embedded precisely.
INDUSTRIAL APPLICABILITY
[0128] As described above, according to the present invention, it
is possible to provide a method for producing a circuit substrate
wherein a circuit chip is disposed on a surface and then pressed
inwards, whereby embedment can be performed easily with high
precision, as well as a circuit substrate produced thereby.
* * * * *